Thrombospondin-1 (TSP-1) is a potent endogenous inhibitor of tumor growth and angiogenesis. It inhibits endothelial cell growth, migration, and tube formation in vitro. In vitro assays have shown that platelet TSP-1 is involved in thrombosis, fibrinolysis, wound healing, inflammation, tumor cell metastasis, and angiogenesis. TSP-1 is the major form of thrombospondin secreted by platelets and endothelial cells.
The in-growth of new capillary networks into developing tumors is essential for the progression of cancer, such as epithelial ovarian cancer (EOC). EOC is the leading cause of death from gynaecological malignancy and the fifth most common cause of cancer-related death in women. In 2013, it is estimated that 22,240 new ovarian cancer cases will be diagnosed in the United States and that 14,030 will succumb to the disease (American Cancer Society: Cancer Facts and Figures 2013. Atlanta, Ga., 2013). The poor ratio of survival to incidence in EOC is related to the high percentage of cases that are diagnosed at an advanced stage and the lack of effective therapies for advanced refractory disease. Despite improvements in surgical techniques, survival of patients with EOC stands at 45% at five years (Jemal et al. Cancer Statistics. 58: 71-96, 2008).
Thus, there is an unmet need in the field for the development of novel anti-angiogenic therapies for effectively treating cancer, such as EOC, to allow for more successful treatment outcomes.